Classically, mascara applicators in the form of brushes were produced using the long-exclusive method of inserting natural or synthetic fibers between two wires that were initially straight. Then, these wires were twisted and held the fibers inserted between them tightly in a particular configuration. These brushes are commonly referred to as wire core brushes.
Wire core brushes have many advantages. But they all have one fundamental disadvantage, namely that the distance of the individual bristles of the set of bristles from one another can only be varied within very limited ranges. It is practically impossible to produce an applicator that has a truly uniform set of bristles around and along the longitudinal direction. Instead, in wire core brushes, the set of bristles is always densest along a helical curve, which follows the twisting of the wires, and is less dense in other regions.
With the ability to produce ever more delicate injection molds, the last approximately ten years have seen the production of increasing numbers of injection molded brushes, which are then used as mascara applicators. These are one-piece brushes in which the bristle support and the bristles protruding from it are produced from one and the same material, generally in one piece by means of injection molding. In order to produce brushes of this kind, injection molds are used that have a main cavity that forms the bristle support. Secondary cavities branch out from this, generally at right angles. Each of the secondary cavities comprises a cavity that forms one bristle.
In this way, it is possible to produce brushes whose set of bristles can be varied in broad ranges with regard to their diameter, length, bristle density, etc. and can therefore be adapted very well to the individual requirements for the application.
In practice, there is continuous demand for providing the injection molded applicators with the same feel as the wire core applicators, even to the extent that the injection molded applicators are provided with bristles of different hardnesses.
To a certain extent, the hardness of the bristles can also be controlled—even when using only a single material—by appropriately setting the bristle diameter; bristles that must be softer are provided with a smaller diameter. There are nevertheless limits to this since the bristles must have a minimum diameter in order not to tear off when being removed from the mold.
Because of this, embodiments have already been proposed in which the bristle-supporting parts, which are composed of a different material, are welded or glued onto an injection molded applicator. This kind of applicator is costly and in addition, a reliable bond is not always assured. Between the rows that are assembled by gluing, it is also not possible to prevent gaps from being left in which the compound to be applied can become permanently lodged, which is disadvantageous because under some circumstances it can become contaminated with germs.
Applicators have also been proposed in which a bristle support that is equipped with bristles composed of a first material has another bristle support clipped to it, which is equipped with bristles composed of a second material. This embodiment is also unsatisfactory because the clipping requires an additional assembly step and once again, cosmetic compound can also collect in the interstice between the parts that are clipped to each other and then constitutes a breeding ground for germs.
By contrast, the object of the present invention is to propose a way that permits the efficient production of brushes, in particular delicate brushes in the form of mascara applicators, which are equipped with bristles composed of different plastics and can be produced as a whole by means of injection molding.